Process of making 2-hydroxyethylhydrazine



Patented Nov. 24, 1953 UNITED STATES hAiTEN'i CFFEQE PROCESS OF MAKINGZ-HYDROXYE'IHYL- HYDRAZINE Gabriel Gever, Oxford, and Charles J. OKecie,Norwich, N. Y., assignors to Eaton Laboratories, Inc., Norwich, N. Y., acorporation of New York No Drawing. Application October 11, 1951, SerialNo. 250,956

Claims.

This invention aims to provide an improved process of2-hydroxyethylhydrazine.

In the past, hydroxyethylhydrazine has been made from hydrazine andethylene oxide by a process which has required operating at reducedtemperatures. In the practice of that process, the reactants were wellcooled (e. g., chilled to ice-salt temperatures during the period whenthey were added to each other) and "then placed in a sealed tube. Thetemperature of the reaction mixture was then permitted to rise toordinary room temperatures and, after a period ranging from 24 to 72hours, the reaction was deemed to be complete. There were produced inthe practice of this process, in addition to the desiredhydroxyethylhydrazine, substantial quantities of undesired products.This old process is not adapted to the production ofhydroxyethylhydrazine on a commercial scale because of the problemsencountered in cooling the reactants and difiiculty in controlling thereaction while the temperature of the reaction mixture rises to roomtemperature. Furthermore, yields obtained in attempting to producehydroxyethylhydrazine on a large scale through the practice of this oldprocess have been limited to about 36-39%.

Other expedients which have been resorted to for the production ofhydroxyethylhydrazine, such as the reaction of ethylene chlorhydrin withhydrazine, yield a salt cake and involve serious diiiiculties in thehandling of the reaction mixture.

We have discovered that the diiiiculties inherent in these pastprocesses of making hydroxyethylhydrazine can be overcome, and asurprisingly high yield of Z-hydroxyethylhydrazine can be obtained, byadding ethylene oxide to hydrazine hydrate at elevated temperatures andmaintaining the reactants at such temperatures until reaction has beencompleted. This can be done within a period which, as compared with thetime required by former processes, is extremely brief.

2-hydrcxyethylhydrazine is made in accordance with our invention byheating, to a temperature within the range of about 30 C. to about 1000., about 2 to about '7 parts of hydrazine hydrate, which may bedissolved in water, in a closed system. 1 part of ethylene oxide isgradually added to the hydrazine hydrate and the temperature of thereaction mixture is maintained within the temperature range of about 30C. to 70 C. during such addition.

We have found that, in the practice of our invention, the reactionproceeds in satisfactory manner at a temperature within the range ofabout 30 C. to about 100 C. We prefer, however, to operate at atemperature of about 70 C. as a somewhat higher yield is obtained atthat temperature, We also prefer, in the practice of our invention, touse a substantial excess of hydrazine hydrate over ethylene oxide. Forinstance, we have obtained a yield of 93% of 2-hydroxyethylhydrazine byadding 1 part of ethylene oxide to 6.3 parts of 100% hydrazine hydrateat 70 C., whereas the yield obtained by adding 1 part of ethylene oxideto 4 parts of 100% hydrazine hydrate at 70 C. was 79%.

The ethylene oxide is added to the hydrazine hydrate at such a rate thatthe positive pressure in the system is in the neighborhood of 20 mm. Aslower rate of addition of ethylene oxide merely serves to prolong thereaction time.

The practice of our invention is illustrated by the following example:

The process is carried out in a closed system connected to a mercurytrap so that positive pressures in excess of 20 mm. will be relieved.118 grams (2 moles) of 85% hydrazine hydrate is brought to a temperatureof 70 C. by immersing the reaction flask in hot water. Ethylene oxide isthen run into the hydrazine hydrate through a tube having an orifice ofapproximately 0.5 mm. as fast as possible without causing the system tovent itself. The flask is immersed intermittently in water of to C. tomaintain the reaction mixture at a temperature of to 72 C. 14 rams (0.32mole) of ethylene oxide is absorbed in 25 minutes at which time theaddition of ethylene oxide is stopped. The excess hydrazine hydrate andwater is removed by distillation under reduced pressure of 25 to 30 mm.at approximately 50 to 55 C. 21 grams of 2-hydroxyethylhydrazine is thenrecovered from the residue by distillation at 112 to 115 C., at 5 to 6mm. This is 86.4% of theory.

What is claimed is:

1. 'Ihe process of making 2-hydroxyethylhyabout 30 C. to about C.,gradually adding 1 part of ethylene oxide to the hydrazine hydrategfizitmaintaging the temperature of the reaction x ure W1 in said tem erSaid addition. p ature range during 2. The process of makingZ-hydroxyethylhydrazine, which comprises reacting ethylene oxide withhydrazine hydrate in a closed system by 3 heating about 2 to about 7parts of hydrazine hydrate to about 70 C., gradually adding 1 part ofethylene oxide to the hydrazine hydrate, and maintaining the temperatureof the reaction mixture at about 70 C. during said addition.

3. The process of making 2-hydroxyethy1hydrazine, which comprisesreacting ethylene oxide with hydrazine hydrate in a closed system byheating about 7 parts of hydrazine hydrate to a temperature within therange of about 30 C. to about 100 C., gradually adding 1 part ofethylene oxide to the hydrazine hydrate, and maintaining the temperatureof the reaction mixture within said temperature range during saidaddition.

4. The method of making 2-hydroxyethy1hydrazine, which comprisesreacting ethylene oxide with hydrazine hydrate in a closed system byheating about 2 to about 7 parts of hydrazine hydrate to a temperaturewithin the range of about 30 C. to about 100 C., adding about 1 part ofethylene oxide to the hydrazine hydrate at such a rate that a positivepressure in the neighborhood of 20 mm. is maintained in the systemduring the addition, and maintaining the 4 temperature of the reactionmixture within said temperature range during said addition.

5. The method of making 2-hydroxyethylhydrazine, which comprisesreacting ethylene oxide with hydrazine hydrate in a closed system byheating about 8.5 parts by Weight of 85% hydrazine hydrate to about 70C., adding 1 part by weight of ethylene oxide to the hydrazine hydrateat such a rate that a positive pressure in the neighborhood of 20 mm. ismaintained within the system during the addition, and maintaining thetemperature of the reaction mixture at about 70 C. to 72 C. during saidaddition.

GABRIEL GEVER. CHARLES J. OKEEFE.

References Cited in the file of this patent UNITED STATES PATENTS NameDate Graenacher et a1. Mar. 13, 1945 OTHER REFERENCES Number

1. THE PROCESS OF MAKING 2-HYDROXYETHYLHYDRAZINE, WHICH COMPRISESREACTING ETHYLENE OXIDE WITH HYDRAZINE HYDRATE IN A CLOSED SYSTEM BYHEATING ABOUT 2 TO ABOUT 7 PARTS OF HYDRAZINE HYDRATE TO A TEMPERATUREWITHIN THE RANGE OF ABOUT 30* C. TO ABOUT 100 C., GRADUALLY ADDING 1PART OF ETHYLENE OXIDE TO THE HYDRAZINE HYDRATE, AND MAINTAINING THETEMPERATURE OF THE REACTION MIXTURE WITHIN SAID TEMPERATURE RANGE DURINGSAID ADDITION.